Cavity reactor with two stage separation

ABSTRACT

A colloidal gas core nuclear reactor having a high tensile strength outer semispheroidal pressure shell enclosing a moderator body member which surrounds a central cavity with an expanding nozzle at one end thereof. The greatest cavity radius is at the end remote from the nozzle. Hydrogen gas is supplied to the cavity to provide a vortex fow within the cavity. A conical duct is provided between the throat of the nozzle and the expansion portion of the nozzle. A groove and particle catcher is provided between the duct and expansion portion of the nozzle. The groove leads to a particle outlet duct.

[ 1 Jan. 30, 1973 United States Patent 1 Von Ohain et al.

[54] CAVITY REACTOR WITH TWO STAGE SEPARATION [75] Inventors: Hans J. l.Von Ohain, Dayton, Ohio; Melvin R. Keller, Pittsburgh, Pa.

[73] Assignee: The United States of America as represented by theSecretary of the United States Air Force [22] Filed: Jan. 13,1970

[21] Appl. No.: 2,598

[52] US. Cl. ..176/45, 60/203, 176/39 [51] lnt.Cl. ..G21c 3/44 [58]Field of Search ..l76/45, 39, 52; 60/203 [56] References Cited UNITEDSTATES PATENTS 3,202,582 8/1965 Rom ..l76/39 X 3,270,496 9/1966 Rom..l76/39 X 9/1968 Hunteretal. ..60/203 12/1970 McLaffer ty ..l76/S2 [57]ABSTRACT A colloidal gas core nuclear reactor having a high tensilestrength outer semispheroidal pressure shell enclosing a moderator bodymember which surrounds a central cavity with an expanding nozzle at oneend thereof. The greatest cavity radius is at the end remote from thenozzle. Hydrogen gas is supplied to the cavity to provide a vortex fowwithin the cavity. A conical duct is provided between the throat of thenozzle and the expansion portion of the nozzle. A groove and particlecatcher is provided between the duct and expansion portion of thenozzle. The groove leads to a particle outlet duct.

v 12 g /0 Z 1 17 f/ x H 120 l J a l CAVITY REACTOR WITH TWO STAGESEPARATION In a copending invention disclosure entitled Colloidal-GasCore Reactor Ser. No. 2597, filed Jan. 13, 1970 there is disclosed anuclear dust core reactor of the type wherein the reactorcavityconfiguration and expellant gas injection means are such thatduring operation the atomic reactive material in the form of fine powderor the like is maintained out of contact with the reactor cavity walls.

In our invention above identified as well as in prior art devices avortex flow is intentionally set up within the reactor cavity whereby amixture of expellant gas (Hydrogen) and reacting nuclear material areseparated, with the clean gas being discharged and the nuclear materialbeing retained in the reactor cavity.

When the reactor cavity is operated at a high mass loading ratio ofreactive material to expellant gas there is the possibility that nuclearmaterial in the form of dust or metallic particles in the size order ofunder ten microns may escape in the stream of expellant gas. In order toconserve the supply of nuclear fuel, it is desirable to recapture suchadditional particles and return them to the reactor cavity.

The present invention relates to an improved dust core reactor systemwherein particle separation is carried out in a two stage process. Inaccordance with the invention this is accomplished by interposing anexternal separator in the line of flow from the reactor cavity. In thesecond separator unit the residual rotation of the vortex core is reliedupon to centrifuge the remaining reactive dust particles onto thechamber walls, the same being trapped and collected prior to expansionof the expellant gas in a rocket nozzle.

The invention will be clear by reference to the appended drawing takenin conjunction with the corresponding description.

The single FIGURE of the drawing, illustrates a schematic side elevationof the elements constituting the invention.

Referring now to the drawing, the reference numeral 1 generallyindicates a dust core reactor of the type specifically disclosed by thepresent inventors in the above identified invention disclosure. Thereactor 1 includes a semispherical pressure resisting shell 2 enclosinga moderator body 3 made of beryllium and while shown as a unitary bodyis preferably constructed of a number of individual parts assembled as aunitary whole. The pressure shell 2 and moderator body 3 are stationaryand connected by conduits l and 16 to an external tank of expellant gasin the form of liquid hydrogen. The conduit forms a part of a well knownregenerative cooling system shown schematically at 17 whereby the liquidgas is passed seriatim through passages formed in the moderator body 3and then injected into the reactor cavity. The reactor cavity generallyindicated by the reference character C has a wall portion 4 forming thethroat of the rocket nozzle. The wall then is formed with a conicalportion 5 joining a radially outward extending portion 6 of convex shapewhich merges with an annular zone 7 with radial walls, one being therear wall 8 of straight radial extent from the central horizontal axis.Circumferential rows of injection nozzles 10 are fed from annularpassages 11. All of the annular passages 11 are connected to theregenerative cooling system supply of expellant gas under high pressureby suitable connections (not shown) in the moderator body 3. The nozzles10 adjacent the throat 4 spill cool gas over the throat with atangential whirl component as well as some of the discharge passing upthe cavity wall 5.

At its radial outermost point the reactor cavity C in the portion 7thereof is provided with an annular manifold 13 suitably connected byconduits 12 with the regenerative cooling system gas supply. Relativelycool gas is discharged from the manifold space 13 through passages (notshown) between vanes 14 which induces a strong tangential as well asradial component to the gas discharge. The underside of the vanes 14 areconvex so that gaseous fluid contacting the vanes will flow off with aninwardly directed centrifugal force displacing any reactive materialinto the reactor cavity and preventing contact with the cavity walls inthe region of high dust loading 7. The upper portions of the walls ofthe zone 7 are also washed by additional nozzles 10 positioned at eachend of the vanes 14 and directing streams of hydrogen radially inward.

When a critical quantity of nuclear fuel in finely divided form ispresent in the reactor cavity C and expellant gas is admitted from highvelocity jets with a tangential component from the various sets ofnozzles 10 and swirl vanes 14, a strong vortex flow is set up in thereactor cavity C as indicated by the arrows. The radially inward flowalong the rear wall 8 turns axially and joins the intensely spinningvortex core and flows axially toward the rocket nozzle throat 4. Theintense centrifugal force fields set up in the reactor cavity C tends tocentrifuge all particles radially outward with a maximum loading in theannular zone 7. The reacting particles intermix with the expellant gasand heat the same to very high temperatures. The particles returning inthe downflow along wall 8 enter the intense centrifugal force fieldgenerated by the vortex core and are centrifuged outward prior to theclean gas passing into the throat section 4. There is, however, apossibility that, under high loading operating conditions, before allfine particles are centrifuged out of the vortex core they may pass thethroat 4 of the rocket nozzle and be lost in the outgoing expellant gasstream. To obviate this, the nozzle throat 4 forms the entrance to anelongate conical duct passage 26 interposed between the nozzle throat 4and the conventional exhaust nozzle 20 formed by the housing 25. Theduct passage 26 is formed by a conical casing 27 abutting the throat 4and positioned between the throat 4 and the expansion nozzle housing 25.Adjacent its downstream end the casing 27 is provided with an annularextension 28 having an internal radially extending annular groove 30.The groove 30 is formed at its outer end with a circumferential circularpassage 31 of progressively increasing diameter to form a conventionalscroll-type diffuser which is connected at its outlet to a returnconduit or duct 32. The duct 32 which preferably is made with a suitableheat resistant inner liner (not shown) is connected at its return end toa nozzle 35 positioned adjacent the horizontal spin axis and adapted todischarge gas and entrained reactive particles tangentially into thereactor cavity C. An annular projection 29 adjacent the groove 30 actsas a catcher for the fine particles.

Operation of the device is as follows. With the dust core reactor 1 inoperation, expellant gas at high temperature passes out of the reactorcavity C at the constricted throat section 4 thereof and movesdownstream to the left as indicated by the arrows in FIG. 1. Theexpellant gas is moving with a subsonic axial velocity and is spinningdue to vortex action at either subsonic or supersonic velocity. The flowis accentuated by the tangential coolant gas jets flowing over thethroat section 4 from the nozzle set 11 adjacent thereto. The heated gasmoving downstream through the duct passage 26 will have its axialvelocity increased to supersonic. The vortex spin continuing into theduct passage 26 will centrifuge out any residual reactive particlespassing through throat 4 and these particles will collect on and movealong the duct passage 26 until they encounter catcher 29 and the radialgroove 30 where they will be trapped and move outward into the scrollpassage 31 along with some expellant gas. The pressure of the expellantgas in the diffuser scroll 31 is higher than the low subatmosphericpressure adjacent the injection nozzle 35 so that there is a continualflow induced from dust collecting groove 30 through scroll diffuserpassage 31, return conduit 32 and nozzle 35 to insure return to thereactor cavity C of all reactive material separated in the duct passage26.

Any conventional control means for externally moderated reactors may beprovided, for example, such as a plurality of control rods 37, one ofwhich is shown.

While a specific form of dust core reactor is herein disclosed, it willbe understood that the invention is applicable to reactors having moreconventional configuration and where the dust loading ratio is such thatreactive material contacting the walls is not so serious a problem. Forexample, the reactor cavity may be generally cylindrical in form withexpellant gas injection nozzles arranged around the completecircumference of the chamber walls to continually wash off and displaceany nuclear material tending to collect there. The cavity may furtheremploy other suitable expedients such as disclosed in our aforementioneddisclosure.

We claim:

1. In combination with a vortex flow dust core nuclear reactor having anexpellant gas and a critical mass of nuclear particles within a chamber;an expansion nozzle and means for providing a circumferential flow ofhydrogen gas within the chamber to separate the nuclear particles fromthe expellant gas; an apparatus for removing nuclear particles from theexpellant gas comprising a second particle separation unit; said nozzlebeing spaced from said chamber by means of the second separation unit;said second particle separation unit including a conical casingconnected at one end to the output of said chamber and at the other endto the input of said expansion nozzle; said nozzle and said secondseparation unit being coaxial with said chamber; and means adjacent theinterior surface of said expansion nozzle for removing nuclear particlesfrom the conical casing which have been centrifuged out of saidexpellant gas.

2. The device as recited in claim 1 wherein said means for removingnuclear particles from said casing includes an internal annular groovein said conical casing adjacent said expansion nozzle; an annular meansconnected to said expansion nozzle and pro ecting into said conicalcasing, between said groove and said expansion nozzle for catchingnuclear particles and a circular outlet passage of increasing radiusconnected to said groove.

1. In combination with a vortex flow dust core nuclear reactor having anexpellant gas and a critical mass of nuclear particles within a chamber;an expansion nozzle and means for providing a circumferential flow ofhydrogen gas within the chamber to separate the nuclear particles fromthe expellant gas; an apparatus for removing nuclear particles from theexpellant gas comprising a second particle separation unit; said nozzlebeing spaced from said chamber by means of the second separation unit;said second particle separation unit including a conical casingconnected at one end to the output of said chamber and at the other endto the input of said expansion nozzle; said nozzle and said secondseparation unit being coaxial with said chamber; and means adjacent theinterior surface of said expansion nozzle for removing nuclear particlesfrom the conical casing which have been centrifuged out of saidexpellant gas.
 1. In combination with a vortex flow dust core nuclearreactor having an expellant gas and a critical mass of nuclear particleswithin a chamber; an expansion nozzle and means for providing acircumferential flow of hydrogen gas within the chamber to separate thenuclear particles from the expellant gas; an apparatus for removingnuclear particles from the expellant gas comprising a second particleseparation unit; said nozzle being spaced from said chamber by means ofthe second separation unit; said second particle separation unitincluding a conical casing connected at one end to the output of saidchamber and at the other end to the input of said expansion nozzle; saidnozzle and said second separation unit being coaxial with said chamber;and means adjacent the interior surface of said expansion nozzle forremoving nuclear particles from the conical casing which have beencentrifuged out of said expellant gas.